Field of the Invention
The present invention relates to a vibration isolator that is applied to, for instance, a motor vehicle or an industrial machine so as to absorb and attenuate vibrations of a vibration generator such as an engine.
Priority is claimed on Japanese Patent Application No. 2014-167273, filed Aug. 20, 2014, the content of which is incorporated herein by reference.
Description of Related Art
Conventionally, such a vibration isolator has been known as being made up of a tubular first mounting member that is connected to one of a vibration generator and a vibration absorber, a second mounting member that is connected to the other, an elastic body that connects these mounting members, and a partition member that partitions a liquid chamber in the first mounting member within which a liquid is enclosed into a primary liquid chamber and a secondary liquid chamber. The partition member is formed with a restriction passage that communicates the primary and secondary liquid chambers with each other. In the vibration isolator, when vibration is input, both of the mounting members are relatively displaced while elastically deforming the elastic body, change a liquid pressure of the primary liquid chamber, and cause the liquid to flow to the restriction passage, thereby absorbing and attenuating the vibration.
Incidentally, in the vibration isolator, for example, when a great load (vibration) is input due to, for instance, roughness of a road surface, the liquid pressure of the primary liquid chamber is sharply raised, and then a load is input in the opposite direction by, for instance, rebound of the elastic body, a pressure of the primary liquid chamber sometimes abruptly becomes a negative pressure. Due to such an abrupt change in pressure, cavitation occurs, which creates numerous bubbles in the liquid. Further, due to the cavitation collapse in which the created bubbles collapse, abnormal noises sometimes occur.
Thus, for example, like a vibration isolator disclosed in Japanese Unexamined Patent Application, First Publication No. 2012-172832, a constitution in which a valve body is provided inside the restriction passage, and thereby even when vibration having a large amplitude is input, the change to the negative pressure in the primary liquid chamber is limited is known.